If the lambda has a capture pack, it cannot be used unexpanded within the
body of the lambda. If you want to expand the pack across multiple lambdas,
don't capture the whole pack.
Tested x86_64-pc-linux-gnu, applying to trunk.
gcc/cp/ChangeLog:
PR c++/97358
* pt.c (check_for_bare_parameter_packs): Diagnose use of
capture pack.
gcc/testsuite/ChangeLog:
PR c++/97358
* g++.dg/cpp0x/lambda/lambda-variadic11.C: New test.
---
gcc/cp/pt.c | 17 +++++++++++-----
.../g++.dg/cpp0x/lambda/lambda-variadic11.C | 20 +++++++++++++++++++
2 files changed, 32 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-variadic11.C
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 555dc47b464..e98bf83117d 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -4230,11 +4230,6 @@ check_for_bare_parameter_packs (tree t, location_t loc
/* = UNKNOWN_LOCATION */)
if (!processing_template_decl || !t || t == error_mark_node)
return false;
- /* A lambda might use a parameter pack from the containing context. */
- if (current_class_type && LAMBDA_TYPE_P (current_class_type)
- && CLASSTYPE_TEMPLATE_INFO (current_class_type))
- return false;
-
if (TREE_CODE (t) == TYPE_DECL)
t = TREE_TYPE (t);
@@ -4244,6 +4239,18 @@ check_for_bare_parameter_packs (tree t, location_t loc
/* = UNKNOWN_LOCATION */)
cp_walk_tree (&t, &find_parameter_packs_r, &ppd, ppd.visited);
delete ppd.visited;
+ /* It's OK for a lambda to have an unexpanded parameter pack from the
+ containing context, but do complain about unexpanded capture packs. */
+ if (current_class_type && LAMBDA_TYPE_P (current_class_type)
+ && CLASSTYPE_TEMPLATE_INFO (current_class_type))
+ for (; parameter_packs;
+ parameter_packs = TREE_CHAIN (parameter_packs))
+ {
+ tree pack = TREE_VALUE (parameter_packs);
+ if (is_capture_proxy (pack))
+ break;
+ }
+
if (parameter_packs)
{
if (loc == UNKNOWN_LOCATION)
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-variadic11.C
b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-variadic11.C
new file mode 100644
index 00000000000..aa4ffd70df7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-variadic11.C
@@ -0,0 +1,20 @@
+// PR c++/97358
+// { dg-do compile { target c++11 } }
+
+template <typename... T> void foo (T... x) {}
+
+template <typename... T> void bar (T... x)
+{
+ foo ([x...] { return x; }...); // { dg-error "not expanded|no parameter
packs" }
+#if __cpp_init_captures >= 201803L
+ foo ([...y = x] { return y; }...); // { dg-error "not expanded|no parameter
packs" "" { target c++20 } }
+#endif
+}
+
+void
+test ()
+{
+ bar ();
+ bar (1);
+ bar (2.0, 3LL, 4);
+}
base-commit: 87d75a11a5cb93668ae0bf6d97030e01b2eae3f2
--
2.18.1
